WO2016126136A1 - Ue discovery method and system in d2d network - Google Patents

Abstract

The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data transmission rate beyond a 4G communication system such as LTE. The present disclosure provides a method for performing device to device (D2D) discovery by a user equipment (UE), which is out of the coverage area serviced by a base station, in a wireless communication network, the method comprising the operations of: receiving pre-configuration information for transmitting a discovery message; and transmitting the discovery message in a transmission resource determined on the basis of the pre-configuration information, wherein the pre-configuration information includes a list of pools for transmitting the discovery message, and the transmission resource is determined from the list of pools.

Description

UE discovery method and system in D2D network

The present disclosure relates to a user equipment (UE) discovery method and system, and to a UE discovery method and system in a device to device (D2D) network.

Efforts are being made to develop improved 5G (5 ^th- Generation) or pre-5G communication systems to meet the increasing demand for wireless data traffic since the commercialization of 4G (4 ^th- Generation) communication systems. . For this reason, a 5G communication system or a pre-5G communication system is referred to as a Beyond 4G network communication system or a post LTE system.

In order to achieve high data rates, 5G communication systems are being considered for implementation in the ultra-high frequency (mmWave) band (e.g., 60 gigabyte (60 GHz) band). In 5G communication systems, beamforming, massive array multiple input and output (FD-MIMO), and full dimensional MIMO (FD-MIMO) are used in 5G communication systems to mitigate the path loss of radio waves and to increase the propagation distance of radio waves. Array antenna, analog beam-forming, and large scale antenna techniques are discussed.

In addition, in order to improve the network of the system, 5G communication systems have advanced small cells, advanced small cells, cloud radio access network (cloud RAN), ultra-dense network (ultra-dense network) Device to device communication (D2D), wireless backhaul, moving network, cooperative communication, coordinated multi-points, and interference cancellation The development of such technology is being done.

In addition, in 5G systems, advanced coding modulation (ACM), hybrid FSK and QAM modulation (SWM) and sliding window superposition coding (SWSC), and advanced access technology, FBMC (filter bank multi carrier) and NOMA Non-orthogonal multiple access (SAP), and sparse code multiple access (SCMA) are being developed.

A general D2D discovery operation scenario is described as follows.

In LTE systems, sidelink transmission (also known as device to device transmission or D2D transmission) may be performed in the uplink frequency spectrum (in case of frequency division duplex (FDD)) or in uplink subframe (in time division duplex (TDD)). ) Can work.

Sidelink transmission is restricted to a subset of uplink resources, i.e., a subset of subframes in the time domain or a subset of resource blocks (RBs) in the frequency domain.

Sidelink transmission may provide two types of Proximity based services (ProSe), that is, direct discovery and direct communication.

1 is a diagram illustrating a scenario where UEs in two neighboring cells discover each other.

In ProSe discovery, UEs in close proximity to each other may discover each other. As illustrated in FIG. 1, the UE-4 100 present in the first cell 110 may not only have UE-3 104 in the neighbor cell 120 but also UE-5 102 in the same cell 110. Can be discovered.

Each UE may transmit discovery messages using discovery resources in a discovery resource pool configured by the network, and may receive discovery messages transmitted from other UEs in the same cell or neighbor cells.

Depending on how resources are allocated, two types of discovery procedures can be defined. The first type of discovery procedure is a procedure in which each UE selects a discovery resource based on a rule predefined for it. A second type of discovery procedure is a procedure in which resources for discovery message transmission are allocated to each UE by a base station eNB.

Synchronization is a prerequisite for sidelink transmission. In order to enable synchronization between the UEs, each eNB, at a fixed period (eg, 40 ms), has a Sidelink synchronization signal (SLSS) or SideLink Synchronization Sequence (SSS). You can set up some synchronization resources for transmission and set up some essential system information.

Each cell has its own SLSS, which may consist of a primary SLSS and a secondary SLSS.

The eNB may instruct SLSS transmission to any UE, and a UE that satisfies a predefined triggering condition may transmit the SLSS.

The transmitted SLSS can be used by the UE to obtain synchronization of time and frequency for sidelink transmission or reception. In addition, the SLSS transmission in one cell allows the UEs of neighboring cells to synchronize with the one cell to discover each other.

System information for sidelink transmission may be derived from a parameter signaled from the eNB, or may be derived from a preset parameter.

In the D2D discovery, the following matters become an issue.

When network coverage is not available, for example in the event of network failure, attenuation due to the local environment, or simple lack of coverage, the ability to maintain ProSe discovery must be ensured, especially in public safety. It needs to be guaranteed for safety purposes.

2 illustrates D2D discovery of out of coverage and partial coverage scenarios.

In FIG. 2, if the network (ie, eNB 200) is not available, out-of-coverage (OOC) UEs (eg, UE-1 202 and UE-2 204) Scheme to enable discovery between the UE and the UE outside the coverage (eg, UE-3 206) and the UE in-coverage (IC) (eg, UE-4 212) and It is required to consider how to enable discovery between the UE-5 214 (ie, partial coverage scenario).

Accordingly, what is needed is a design of a method, solution, or system that will enable ProSe discovery in out-of-coverage and partial coverage scenarios.

Accordingly, the present disclosure provides a ProSe discovery pre-configuration method, a synchronization procedure, and a discovery method and a system between an in-coverage UE and an out-of-coverage UE.

The present disclosure relates to a method for performing device to device (D2D) discovery of a user equipment (UE) that is out of coverage serviced by a base station in a wireless communication network, the method comprising: receiving pre-configuration information for transmission of a discovery message To act; And transmitting a discovery message in a transmission resource determined based on the preset information, wherein the preset information includes a pool list for transmitting the discovery message, and the transmission resource is the pool list. We propose a method characterized in that it is determined from.

In addition, the present disclosure receives pre-configuration information for transmission of a discovery message in a user equipment (UE) that is out of coverage serviced by a base station in a wireless communication network, and based on the preset information. A control unit controlling to transmit a discovery message in the determined transmission resource; And a transceiver configured to receive the preset information and transmit the discovery message under the control of the controller, wherein the preset information includes a pool list for transmitting the discovery message, wherein the transmission resource is the transmission resource. We propose a UE characterized in that it is determined from a full list.

In addition, the present disclosure provides a method of performing device to device (D2D) discovery of a user equipment (UE) in a wireless communication network, the method comprising: receiving a message including pre-cofiguration information for transmitting a D2D discovery message; Determining to act as a synchronization reference UE when receiving a command from a base station or meeting a predefined condition; Transmitting, in a transmission resource determined based on the preset information, a synchronization signal used for synchronization acquisition of time and frequency, and transmitting system information including transmission timing information of a discovery message; And transmitting a discovery message in a transmission resource determined based on the preset information. Optionally, the preset information includes at least one of a number of retransmissions of a discovery message, a number of subframe bitmaps during one discovery period, and information indicating a discovery offset. Optionally, the predefined condition is based on a combination of one or more of whether the UE is within coverage of the network and whether a reference signal received power (RSRP) of the received synchronization signal is less than a threshold included in the preset information. Is determined by Optionally, the UE is a UE in coverage or a UE out of coverage. Optionally, the method further comprises receiving configuration information of a resource pool to be used for transmission of the synchronization signal, the system information and the discovery message via a system information block (SIB) 19. Optionally, the method further comprises reporting the reception of the second synchronization signal to the base station when receiving a second synchronization signal from the UE out of coverage. Optionally, the method further comprises receiving from the base station reconfiguration information of a resource pool to be used for transmission of the synchronization signal, the system signal and the discovery message; And transmitting at least one of the synchronization signal, the system signal, and the discovery message by using a resource pool determined based on the reset information. Optionally, if the synchronization reference UE that the UE has is a UE in coverage, the ID of the transmitted synchronization signal is set equal to the ID of the synchronization signal of the synchronization reference UE. Optionally, if the synchronization reference UE that the UE has is not a UE in coverage, the ID of the transmitted synchronization signal is selected within a set of synchronization signal IDs for cases other than coverage.

In another aspect, the present disclosure is to receive a message including pre-cofiguration information for transmitting a D2D discovery message in a user equipment (UE) performing device to device (D2D) discovery in a wireless communication network, the command from the base station Received or if it satisfies a predefined condition, and decides to act as a synchronization reference UE, and transmits a synchronization signal used to acquire the synchronization of time and frequency in the transmission resources determined based on the preset information, A control unit configured to transmit system information including transmission timing information of the discovery message and to transmit a discovery message in a transmission resource determined based on the preset information; And a transmitter / receiver configured to transmit or receive the message, the command, the synchronization signal, the system information, and the discovery message under the control of the controller. Optionally, the preset information includes at least one of a number of retransmissions of a discovery message, a number of subframe bitmaps during one discovery period, and information indicating a discovery offset. Optionally, the predefined condition is based on a combination of one or more of whether the UE is within coverage of the network and whether a reference signal received power (RSRP) of the received synchronization signal is less than a threshold included in the preset information. Is determined by Optionally, the UE is a UE in coverage or a UE out of coverage. Optionally, the controller is configured to receive configuration information of a resource pool to be used for transmission of the synchronization signal, the system signal, and the discovery message via a system information block (SIB) 19. Optionally, when the controller receives the second synchronization signal from the UE other than the coverage, the controller further performs an operation of reporting the reception of the second synchronization signal to the base station. Optionally, the controller receives reconfiguration information of a resource pool to be used for transmission of the synchronization signal, the system signal, and the discovery message from the base station, and uses the resource pool determined based on the reset information. And transmit at least one of the synchronization signal, the system signal, and the discovery message. Optionally, if the synchronization reference UE that the UE has is a UE in coverage, the ID of the transmitted synchronization signal is set equal to the ID of the synchronization signal of the synchronization reference UE. Optionally, if the synchronization reference UE that the UE has is not a UE in coverage, the ID of the transmitted synchronization signal is selected within a set of synchronization signal IDs for cases other than coverage.

The present disclosure can dramatically increase the discovery success rate between UEs in a partial coverage scenario in which an in-coverage UE and a non-coverage UE coexist.

Since the present disclosure provides a specific method of synchronization that the UE must perform in advance for discovery, it allows a synchronization reference UE (UE) to increase the discovery success rate of the UE, and provides signals and system information necessary for synchronization from the synchronization reference UE. Allows better reception

The present disclosure allows a non-coverage UE to successfully discover with a UE in coverage.

In addition, the present disclosure may provide details about parameters to be reflected in a specification for discovery operation.

1 illustrates a scenario where UEs in two neighboring cells discover each other;

2 illustrates D2D discovery of out of coverage and partial coverage scenarios;

3A illustrates an example of sidelink synchronization resource allocation for in-coverage operation in accordance with the present disclosure;

3B is an illustration of sidelink synchronization resource allocation for out of coverage operations in accordance with the present disclosure;

4 illustrates the use of a symbol in a D2D synchronization resource in accordance with the present disclosure;

5 illustrates D2D discovery synchronization in an out of coverage scenario and a partial coverage scenario according to the present disclosure;

6 is a flow chart illustrating a SyncRef UE initialization procedure of a UE performing discovery according to the present disclosure;

7 is a flow chart illustrating a SLSS selection and synchronization subframe selection procedure according to the present disclosure;

8 illustrates a selection of SLSSID in a partial coverage scenario according to the present disclosure;

9 illustrates a selection of synchronization subframes in a partial coverage scenario according to the present disclosure;

10A is an exemplary subframe bitmap of an in-coverage resource pool;

10B is an exemplary subframe bitmap of an out of coverage resource pool;

11A illustrates an example of a resource when discovery transmission is repeated two times in the present disclosure;

11B is an exemplary resource diagram when discovery transmission is repeated 4 times in the present disclosure.

12A illustrates an example resource pool in an in-coverage case for in-coverage UE and out-of-coverage UE to discover each other according to the present disclosure;

12B illustrates an example of an out-of-coverage resource pool for the in-coverage UE and the out-of-coverage UE to discover each other according to the present disclosure;

13 illustrates an example of a detection reporting scenario of an out of coverage signal by an in-coverage UE according to the present disclosure;

14 illustrates a discovery procedure between an in-coverage UE and an out-of-coverage UE based on an out-of-coverage signal detection report by the in-coverage UE in the present disclosure;

15 illustrates a configuration of a UE device according to the present disclosure;

16 is a diagram illustrating a configuration of an eNB device according to the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description will be omitted. Terms to be described later are terms defined in consideration of functions in the present disclosure, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Prior to the detailed description of the present disclosure, examples of the meanings that can be interpreted for several terms used herein are given. However, it should be noted that the present invention is not limited to the example of interpretation given below.

A base station is a subject that communicates with a terminal, and may also be referred to as a BS, a NodeB (NB), an eNodB (eNB), an access point (AP), or the like.

A user equipment is a subject that communicates with a base station and may also be referred to as a UE, a mobile station (MS), a mobile equipment (ME), a device, a terminal, or the like.

Direct discovery and direct communication, which are examples of ProSe, refer to discovery and communication that are directly performed between terminals, respectively. Hereinafter, 'discovery' and 'sidelink (sl)' will be described. Communication).

In-coverage means within coverage of an available eNB 210, and partial coverage refers to a case where a UE in coverage and a UE outside coverage coexist.

A. ProSe  Preset Methods for Discovery

In order to enable ProSe operation when the UE is out of network coverage, a setting for allowing the UE to perform ProSe operation may be pre-configured, and the preset may be called 'ProsePreconfiguration'.

The ProsePreconfiguration may be preset in a Universal Integrated Circuit Card (UICC) or mobile equipment (ME).

The ProsePreconfiguration may include at least one of the settings of Table 1 as described in 3rd generation partnership project (3GPP) technical specification (TS) 36.331.

Table 1

To enable ProSe discovery when the UE is out of network coverage, a ProSe discovery related preset ' ProsePreconfigDisc ' may be added to the ProsePreconfiguration . ProsePreconfigDisc May include a list ' ProsePreconfigDiscPoolList ' of individual resource pools for discovery as shown in Table 2.

TABLE 2

When the UE is out of network coverage, the UE may use at least a preset resource pool to perform discovery with another UE.

In order to perform discovery when some UEs are in coverage and some UEs are out of coverage, all UEs (ie, both in coverage and non-coverage UEs) must have a resource pool set up for discovery, the resource pool being a discovery in a neighbor cell. It may be a union of a resource pool for transmission / reception and a resource pool for out-of-coverage discovery transmission.

The ProsePreconfiguration ProsePreconfigSync included in Note that can be commonly used for sidelink communication and discovery.

For example, the ProsePreconfigSync Parameter that is, sync-OffsetIndicator1 and sync- OffsetIndicator2 of resources in the synchronization may be different from each other with respect to the side links in communication with discovery. Or, sync- OffsetIndicator1, but it may be common to the side links in communication with discovery, sync- OffsetIndicator2 may be different from each other with respect to the side links in communication with discovery.

In addition, the ProsePreconfigSync SyncTxThreshOoC within May be different for sidelink communication and discovery. This means that syncTxThreshOoCComm and syncTxThreshOoCDisc for sidelink communication and discovery respectively in non-coverage scenarios. Means that can exist.

Specific synchronization parameters for sidelink communication and discovery allow for a more efficient manner of synchronizing between communicating UEs or synchronizing between discovered UEs.

B. Perform Discovery UEs  Synchronization procedure between

The purpose of the synchronization procedure is to provide synchronization information to the UE outside of network coverage.

The synchronization information is provided by a UE acting as a synchronization reference (hereinafter referred to as a 'SyncRef UE' or a 'synchronization reference UE') and transmitted from a synchronization resource set by the network or from a preset synchronization resource. Can be.

The SyncRef UE (synchronization reference UE) may transmit not only SLSS but also sidelink system information known as MIB-SL (Master Information Block for Sidelink). The MIB-SL may include timing information and at least one additional configuration parameter that enables system information to be delivered to the UE out of coverage.

When the UE is in network coverage, the content of the MIB-SL may be derived from the parameter signaled by the eNB.

When the UE is out of coverage, if the UE selects another UE as a synchronization criterion, the contents of the MIB-SL may be derived from the received MIB-SL (ie, parameters included in the MIB-SL). Otherwise, if there is no synchronization reference UE selected by the non-coverage UE, the non-coverage UE may use a preset parameter.

3A and 3B illustrate examples of sidelink synchronization resources for in-coverage and out-of-coverage operations in accordance with the present disclosure.

An example of synchronization resource allocation of in-coverage operation is illustrated in FIG. 3A, and an example of out-of-coverage operation is illustrated in FIG. 3B.

In the in-coverage operation of FIG. 3A, there is one synchronization resource unit 300 every 40 ms. Information for SLSS and MIB-SL transmission may be provided by System Information Block Type 19 (SIB19).

In the out of coverage operation of FIG. 3B, there are two preset synchronization resource units 310, 312 every 40 ms. When the UE becomes a SyncRef UE, the UE receives the SLSS and MIB-SL in one synchronization resource unit (eg 310) and the SLSS and MIB-SL in another synchronization resource unit (eg 312). Send it.

When the out of coverage UE detects the SLSS / MIB-SL from the SyncRef UE in the coverage and derives the timing information, one of the synchronization resource units for the out of coverage operation (eg, 312) Can be aligned with Thus, the synchronized resource unit for the tailored out-of-coverage operation may enable synchronization of the in-coverage UE and the out-of-coverage UE.

One synchronization resource unit occupies one subframe in the time domain and may occupy six central resource blocks (RBs) in the frequency domain.

4 is a diagram illustrating the use of a symbol in a D2D synchronization resource according to the present disclosure.

Each of the diagrams of FIG. 4 illustrates a normal CP and an extended CP case.

During one synchronization resource unit occupying one subframe, the primary SLSS 400 occupies two adjacent symbols, the secondary SLSS 402 also occupies two adjacent symbols, ending with a gap symbol 406. Symbols can be used. The remaining symbols can be used for MIB-SL transmission, two of which can be DMRS symbol 404. DMRS symbol 404 is used for DMRS (Demodulation Reference Signal) transmission to assist in channel measurement and data decoding.

One) SyncRef UE  reset

5 is a diagram illustrating D2D discovery synchronization in an out of coverage scenario and a partial coverage scenario according to the present disclosure.

For an in-coverage UE, the eNB 500 may instruct one UE to become a SyncRef UE and send an SLSS. For example, the eNB may set a syncSourceControl , which is a synchronization reference indication parameter, to the SyncRef UE.

Alternatively, a threshold of Reference Signal Received Power (RSRP) may be used to trigger SLSS transmission.

That is, if the RSRP of the UE is lower than a preset threshold value (eg, syncTxThreshIC ), the UE may be a SyncRef UE to transmit an SLSS, since the UE is likely to be located at a cell edge. to be.

For example, UE-4 502 may be instructed to be a SyncRef UE by eNB 500, and UE-5 504 may also be triggered by an RSRP threshold condition to become a SyncRef UE.

For an out of coverage UE, an RSRP threshold may be similarly defined to trigger SLSS transmission.

If the RSRP of the UE is lower than a preset threshold (eg, syncTxThreshOoC ), the UE may send a SLSS. SyncTxThreshOoC May be included in the preset ProSe parameter (eg, ProsePreconfiguration ).

Taking FIG. 5 as an example, the out of coverage UE-1 510 and UE-3 512 may each be a SyncRef UE triggered by an RSRP threshold condition.

Accordingly, a UE capable of transmitting SLSS may transmit SLSS and MIB-SL in synchronization resources according to a predetermined rule when transmitting a direct discovery announcement and when the conditions of Table 3 are satisfied.

TABLE 3

6 is a flow chart illustrating a SyncRef UE initialization procedure of a UE performing discovery according to the present disclosure.

The UE prepares for transmission of direct discovery (600).

The UE checks if it is within network coverage (605).

As a result of the check 605, if the UE is in coverage of the cell, the UE checks if it is instructed to operate as a SyncRef UE from the eNB (610).

As a result of the check 610, when the UE is commanded to operate as a SyncRef UE, the UE operates as a SyncRef UE and transmits SLSS and MIB-SL in synchronization resources (625). As a result of the check 610, if the UE is not commanded to operate as a SyncRef UE, the UE includes syncTxThreshIC in SIB19 and the RSRP measurement result of the cell is syncTXThreshIC. Check if less than (620).

As a result of the check 620, the RSRP measurement result of the cell is syncTXThreshIC If not less than, the UE does not operate as a SyncRef UE (630).

As a result of the check 605, if the UE is not within the coverage of the cell, the UE indicates that RSRP measurement results of all detected SLSS are syncTxThreshOoC. Check if less than (615).

As a result of the check 615, if the RSRP measurement result of all the detected SLSS is less than syncTxThreshOoC , the UE may operate as a SyncRef UE and transmit SLSS and MIB-SL in synchronization resources (625). As a result of the check 615, RSRP measurement results of all detected SLSS are syncTxThreshOoC If not less, the UE may determine not to operate as a SyncRef UE (630).

As mentioned earlier, ProsePreconfiguration SyncTxThreshOoC included in Is set in common for sidelink communication and discovery, the parameter syncTxThreshOoC can be used directly for discovery.

Alternatively, syncTxThreshOoC May be set differently for sidelink communication and discovery. In this case, syncTxThreshOoC specific to discovery will be used for the out of coverage discovery UE.

2) SLSS  send

For sidelink transmission, there are two sets of SLSSs: SLSS_net consisting of identifiers {0,1, ..., 167} and SLSS_oon consisting of identifiers {168,169, ..., 335}. .

The SLSS sent by the in-coverage UE is in the SLSS_net and is indicated by the eNB, and the SLSS sent by the out-of-coverage UE is selected from the SLSS_oon.

If the SLSS from the SLSS_net is detected, the out of coverage UE may transmit the detected SLSS when a predefined criterion is satisfied.

The UE may select the SLSS and synchronization resource unit subframes as shown in Table 4.

Table 4

7 is a flow chart illustrating a SLSSID selection and synchronization subframe selection procedure according to this disclosure.

The UE is operating as a SyncRef UE (700).

The UE checks if it is within network coverage (702).

As a result of the check 702, when the UE is in coverage, the UE selects the SLSSID included in the received SIB 19 as the ID of the SLSS to be transmitted (730). In addition, the UE may select a sub-frame according to the sync- OffsetIndicator included in the SIB19 (732). The UE transmits a SLSS in the selected subframe using the selected SLSSID (740).

As a result of the 702 check, if the UE is not in coverage, the UE checks if there is a SyncRef UE selected by the UE as a reference of synchronization (704).

As a result of the check 704, if there is a SyncRef UE selected as a criterion of synchronization, the UE checks if the selected SyncRef UE is in coverage (706).

The result of the check 706, the selected when the UE is within coverage SyncRef (e.g., inCoverage within the MIB-SL received from the UE SyncRef Is TRUE), the UE selects an SLSSID equal to the SLSSID of the selected SyncRef UE (720). In addition, the UE selects a sub-frame according to the sync- OffsetIndicator1 or sync- OffsetIndicator2 included in the preset parameters ProSe 724. Therefore, the subframe selected by the UE is different from the SLSS of the selected SyncRef UE. The UE transmits a SLSS in the selected subframe using the selected SLSSID (740).

The result of the check 706, the selected case is not within the coverage SyncRef UE (e.g., inCoverage within the MIB-SL received from the UE SyncRef Is FALSE), the UE checks if the SLSSID used by the selected SyncRef UE is included in the SLSSID set for the case within coverage (708).

As a result of the 708 check, if the SLSSID used by the selected SyncRef UE is not included in the SLSSID set for the case in coverage, the UE selects a SLSSID equal to the SLSSID of the selected SyncRef UE (720). In operation 724, the subframe may be selected, and the SLSS may be transmitted as in operation 740.

As a result of the 708 check, if the SLSSID used by the selected SyncRef UE is included in the SLSSID set for the case within coverage, the UE has an index greater than 168 than the index of the SLSSID of the selected SyncRef UE, if it is out of coverage From the set defined for, select the SLSSID (722). In operation 724, the subframe may be selected, and the SLSS may be transmitted as in operation 740.

On the other hand, if the UE does not have a selected SyncRef UE as a result of the 704 check, the UE randomly selects the SLSSID from the SLSSID set defined for the case out of coverage (710). In addition, the UE selects a sub-frame according to the sync-OffsetIndicator1 or sync- OffsetIndicator2 included in the preset parameters ProSe 712. The UE transmits a SLSS in the selected subframe using the selected SLSSID (740).

8 is a diagram illustrating selection of a SLSSID in a partial coverage scenario according to the present disclosure.

UE-1 800 in coverage may transmit a SLSS having a value of 100 for the SLSSID.

UE-2 (802) out of coverage has UE-1 (800) in coverage as a SyncRef UE, and selects the same value as SLSSID of UE-1 (800) as SLSSID to transmit SLSS.

UE-3 (804) out of coverage has UE-2 (802) out of coverage as a SyncRef UE, and the UE-2 (802) is included in the SLSSID set for the case where it is in coverage. The SLSS can be transmitted by selecting 268, which is 168 larger than the SLSSID of the SLSSID.

9 is a diagram illustrating selection of a synchronization subframe in a partial coverage scenario according to the present disclosure.

ProsePreconfiguration Parameters included in sync- OffsetIndicator1 (900 or 902) and sync- OffsetIndicator2 904 is offset information specifying the position of a synchronization subframe from a direct subframe number (SFN) or a direct frame number (DFN). Subframes 910, 912, and 914 represent subframes that may be used by UE-1 800, UE-2 802, and UE-3 804, respectively.

As mentioned earlier, ProsePreconfiguration Parameters included in sync-OffsetIndicator1 (900 or 902) and sync- OffsetIndicator2 If 904 is set to be common for sidelink communication and discovery, the parameter is directly for discovery of UE-2 802 and UE-3 804 other than UE-1 800 or discovery within coverage. Can be used. Otherwise discovery specific sync- OffsetIndicator1 And sync-OffsetIndicator2 may be set, and parameters specific to the discovery may be used for out-of-coverage discovery UE-2 802 and UE-3 804.

3) MIB - SL  send

MIB-SL transmission by the SyncRef UE may include at least one of timing information and additional configuration parameters illustrated in Table 5.

Table 5

The UE may set the content of the MIB-SL message according to the conditions illustrated in Table 6.

Table 6

Note that the DMRS for sidelink communication and discovery may be different. Other DMRSs, depending on sidelink communication and discovery, allow the out of coverage UE to easily know whether the MIB-SL is sent from the discovery UE or from the sidelink communication UE.

4) SyncRef UE  Select

The procedure illustrated in Table 7 may be applied for SyncRef UE selection of the UE.

TABLE 7

C. Discovery Method

One) Coverage  outside UEs  Discovery between

UEs out of network coverage may perform discovery with each other in a preset resource pool if no signal is detected from the UE in coverage.

2) Coverage  outside UE and Coverage  of mine UE  Discovery between

If the out-of-coverage UE detects a signal from the in-coverage UE, the out-of-coverage UE and the in-coverage UE preferably discover each other. However, if there is a mismatch between the preset for the out-of-coverage case and the setting for the in-coverage case, there will be a problem with the out-of-coverage UE discovering the in-coverage UE and vice versa.

First, if there is a mismatch in resource pool settings (eg, a subframe bitmap in the resource pool or an index of the RB used in the resource pool), the UE will have difficulty discovering each other.

10A and 10B illustrate examples of inconsistencies of a subframe bitmap between an in-coverage resource pool and an out-of-coverage resource pool.

10A illustrates an out of coverage resource pool, and FIG. 10B illustrates an out of coverage resource pool. 10A and 10B, the arrangement of subframes indicated by '1' (that is, the subframes indicated by 'D' in FIG. 10) may include a resource pool within coverage (FIG. 10A) and an out of coverage resource pool. It can be seen that (Fig. 10b) is different from each other. That is, the subframe bitmap is different between the settings in the coverage and the settings outside the coverage, resulting in subframe mismatch in the entire resource pool. The subframe bitmap may be configured of '1' which is allocated for discovery and '0' which is not allocated.

In addition, the RB configuration in the frequency domain may be different in the resource pool and the out of coverage resource pool. Thus, even if the timing of the out of coverage UE is synchronized with the in coverage (ie, cell network), discovery failure may occur due to a mismatch of resources (ie, subframe or RB).

Secondly, setting mismatches in transmission parameters for non-coverage and in-coverage cases can also cause problems for UEs to discover each other.

For example, the number of discovery message repetitions within coverage is set by the eNB, and in case of out of coverage is preset. The number of iterations affects the resources used to send one discovery message.

11A and 11B illustrate an example of a resource in case of discovery transmission with different repetition times (2 or 4) in the present disclosure.

FIG. 11A illustrates a resource pool in case of discovery transmission in two repetitions, and FIG. 11B illustrates a resource pool in case of discovery transmission in four repetitions.

In FIGS. 11A and 11B, unit discovery resources indicated by the same index indicate resources of the same discovery message. One discovery message occupies one subframe in the time domain and two RBs in the frequency domain. In FIG. 11, one subframe * 2 RBs are represented as one unit resource (that is, a unit rectangle) for convenience of understanding.

One discovery message with n repetitions is transmitted in n adjacent subframe (s), and frequency hopping may also differ for different number of repetitions. For example, unit resources 1100 and 1102 denoted as '0' in FIG. 11 (a) represent resources used for two repetitions in one discovery message transmission. In addition, the unit resources 1110, 1112, 1114, and 1116 denoted by “0” in FIG. 11 (b) indicate resources used for four repetitions in one discovery message transmission. Thus, different iterations, even within the same resource pool, can cause problems in receiving discovery messages.

Depending on how the in-coverage resource pool is set by the eNB, the behavior of the out of coverage UE may vary. In the following, a solution is proposed that enables discovery between an in-coverage UE and an out-of-coverage UE, and the behavior of that UE is described. It is assumed that the out-of-coverage UE and the in-coverage UE detect synchronization signals from each other and synchronize with each other. The in-coverage UE and the out-of-coverage UE want to discover each other.

The first solution is for the eNB to set the in-coverage case without considering the presetting for out of coverage.

The motivation of the first solution is to provide full flexibility to the eNB in setting the resource pool and related parameters in coverage. This is because non-coverage scenarios do not occur frequently. The in-coverage resource pool set by the eNB may or may not overlap a preset resource pool for the non-coverage case. In this case, the out of coverage UE may not discover the in-coverage UE, and conversely, the in-coverage UE may not discover the out-of-coverage UE.

In this case, the out of coverage UE may need to blindly detect the discovery message one by one. The out of coverage UE may not be able to combine repeated transmissions of the same discovery message, since the out of coverage UE does not have information on the exact resource pool and setting of corresponding transmission parameters for the case in coverage. to be. Similarly, in-coverage UEs can also attempt blind detection of discovery messages from non-coverage UEs.

The second solution is for the eNB to set the in-coverage case in consideration of the preset for the out-of-coverage case.

The motivation for the second solution is to give priority to considering out-of-coverage scenario support, because out-of-coverage discovery is very important in some cases, such as in public safety applications. There may be several options for configuration for in-coverage operation.

Option 1) The eNB sets the in-coverage resource pool and transmission parameters as the preset for out-of-coverage operation.

Option 2) The eNB sets a subset of the resource pool in case of out of coverage for in-coverage operation. For example, as shown in FIG. 12, the same subframe bitmap as the preset for out-of-coverage operation may be used in the case of coverage, but a small number of bitmap receptions may be used in the case of coverage.

12A and 12B illustrate resources when setting a subset of pre-covered resources for in-coverage operation according to the present disclosure.

12A illustrates a resource pool in case of coverage and FIG. 12B illustrates a resource pool in case of out of coverage. Outside of coverage, three or more subframe bitmaps 1210, 1212, 1214 are used, whereas only two subframe bitmaps 1200, 1202 are used within coverage. That is, a subset of the resource pool in the case of non-coverage is used for in-coverage operations.

In option 1, the resource pool in the in-coverage case set by the eNB is exactly the same as the resource pool in the non-coverage case. If the same transmission parameter is set, the in-coverage UE and the out-of-coverage UE can discover each other without problems.

In option 2, if the same transmission parameter is set, the in-coverage UE and the out-of-coverage UE can discover each other at least for the duration of the in-coverage resource pool.

Compared to the option 1, the option 2 is more flexible, in which the eNB sets a period of resource pool (ie, the number of subframe bitmaps applied) for the in-coverage case in consideration of the traffic load state of the in-coverage UE. Because it can. When the resource required for the UE in coverage is much smaller than the size of the resource pool in case of out of coverage, option 1 may cause a waste of resources, in which case option 2 may be a more efficient approach.

The third solution is for the eNB to make settings for the in-coverage case based on the UE report.

The motivation of the third solution is to set up event triggered when needed.

For example, if the in-coverage UE detects a signal of the out-of-coverage UE (eg, SLSS), the in-coverage UE can report the detected signal to the eNB. After receiving the report from the in-coverage UE, the eNB may know that the UE is in addition to network coverage. If the current setting for the case within the coverage is inconsistent with the out of coverage preset, the eNB may reset the in-coverage resource pool. In other words, if there is no report on the out-of-coverage signal detection, the eNB can set the in-coverage case as the first solution. In addition, upon receiving a report regarding the detection of the out of coverage signal, the eNB may reset the in-coverage resource pool based on the second solution.

13 is an exemplary diagram of a detection report scenario of an out of coverage signal by an in-coverage UE according to the present disclosure.

In the example of FIG. 13, UE-1 800 may detect SLSS 1300 from UE-2 802, where UE-1 800 and UE-2 802 are illustrated in FIG. 9. As described above, the SLSS is transmitted in different synchronization subframes (910 and 912, respectively), so that collision does not occur in the transmission resource. UE-1 800 may report 1302 to the eNB 1310 regarding the detection of the out of coverage SLSS. Upon receiving the report 1302, the eNB 1310 may check whether the setting in the case of coverage may be reset when there is a mismatch with the preset in case of out of coverage. After in-coverage reconfiguration, the in-coverage UE 800 and the out-of-coverage UE (eg, UE-3 804) can successfully discover each other.

An example of a procedure corresponding to the third solution is described in FIG. 14.

14 is a diagram illustrating a discovery procedure between an in-coverage UE and an out-of-coverage UE based on the out-of-coverage signal detection report by the in-coverage UE in the present disclosure.

The eNB 1400 sends SIB19 to the in-coverage UE-1 1402 (1410).

UE-1 1402 in coverage receives SIB19 and, when SIB19 is decoded, performs discovery in a resource pool established by the eNB 1400 (1412). Since UE-2 1404 out of coverage does not receive or decode a signal (eg, SIB19) from the network (ie, eNB), the UE-2 1404 is a preset resource pool for the case out of coverage. Discovery may be performed at 1414. For example, the UE-1 1402 may transmit a discovery message in a resource pool set by an eNB (1416), and the UE-2 1404 may transmit a discovery message in a preset resource pool (1418). ). In this case, due to a mismatch between the in-coverage resource pool and the out-of-coverage resource pool, the UE-1 1402 may not be able to decode the discovery message of the UE-2 1404 (1420), and conversely, the UE-2 1404. May also fail to decode the discovery message of the UE-1 1402 (1422).

The eNB 1400 may instruct the UE-1 1402 to be a SyncRef UE (1430).

The UE-1 1402, which has become a SyncRef UE, may transmit a SLSS and a MIB-SL (1432).

The UE-2 1404 that detects the SLSS from the UE-1 1402 may synchronize with the UE-1 1402 and operate as a SyncRef UE (1434).

The UE-2 1404 operating as a SyncRef UE may transmit a SLSS and a MIB-SL (1436).

UE-1 1402 may detect an SLSS signal from the UE-2 1404 (1438) and report signal detection from an out of coverage UE (ie, the UE-4) to the eNB 1400. (1440).

Upon receiving the report 1440 from the UE-1 1402, the eNB 1400 may reset the resource pool and transmission parameters for the case of coverage (1442) and update and transmit SIB19 (1444).

Receiving the updated SIB19, the UE-1 1402 can decode the SIB19 and update a resource pool configuration as indicated by the SIB19 (1446). The UE-1 1402 may transmit a discovery message in the updated resource pool (1448). The UE-2 1404 may also transmit a discovery message in the out of coverage resource pool (1450). The UE-1 1402 performing discovery in the reset resource pool may successfully decode discovery messages of the UE-2 1404 (1452), and the UE-2 1404 also the UE-1 The discovery message of 1402 can be successfully decoded (1454).

15 is a diagram illustrating a configuration of a UE device according to the present disclosure.

The UE apparatus 1500 may include a transceiver 1510 capable of communicating a signal with an eNB or another UE; And a controller 1520 for controlling the transceiver 1510. Of course, the transceiver 1510 and the controller 1520 may be implemented as a single device.

The controller 1520 is a component that implements the discovery method of the UE described in the present disclosure. That is, all of the above-described operations of the UE may be understood to be performed by the controller 1520.

16 is a diagram illustrating a configuration of an eNB device according to the present disclosure.

The eNB device 1600 may include a transceiver 1610 capable of communicating a signal with a UE; And a controller 1620 for controlling the transceiver 1610. Of course, the transceiver 1610 and the controller 1620 may be implemented as a single device.

The controller 1620 is a component that implements the discovery support method performed by the eNB described in the present disclosure. That is, all of the above-described operations of the eNB may be understood to be performed by the controller 1620.

Description of the procedure illustrated in Tables 1 to 7, and the configuration of the system illustrated in Figures 3 to 16, an example of the configuration of the resource pool, an illustration of the method, etc. for limiting the scope of the present disclosure It should be noted that there is no intention. That is, all the descriptions, resource pool arrangements, components, or steps of operations described in Tables 1-7, and 3-16 above should not be construed as essential components for the practice of the present disclosure, and some elements. Even including only, it can be implemented within a range that does not impair the nature of the present disclosure.

The above-described operations can be realized by providing a memory device storing the corresponding program code to an entity, a function, a base station, or any component in the terminal device of the communication system. That is, the controller of an entity, a function, a base station, or a terminal device can execute the above-described operations by reading and executing a program code stored in a memory device by a processor or a central processing unit (CPU).

The various components, modules, etc. of an entity, function, base station, or terminal device described herein may be a hardware circuit, for example, a complementary metal oxide semiconductor based logic circuit. And hardware circuitry such as firmware and a combination of software and / or hardware and software embedded in firmware and / or machine readable media. As an example, various electrical structures and methods may be implemented using transistors, logic gates, and electrical circuits such as application specific semiconductors.

Meanwhile, in the detailed description of the present disclosure, specific embodiments have been described. However, various modifications may be possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims (15)

A method of performing device to device (D2D) discovery of a user equipment (UE) that exists outside of coverage serviced by a base station in a wireless communication network, Receiving pre-configuration information for transmission of a discovery message; And And transmitting a discovery message in a transmission resource determined based on the preset information. The preset information includes a pool list for transmitting the discovery message, and wherein the transmission resource is determined from the pool list. The method of claim 1, Detecting a signal from a neighbor UE; And The method may further include determining whether a received signal received power (RSRP) of the detected signal is less than a threshold value. The threshold value is included in the preset information. The method of claim 2, If the RSRP is less than the threshold, transmitting at least one of a synchronization signal and system information for D2D communication in a transmission resource determined based on the preset information. The method of claim 1, The preset information may further include at least one of a number of retransmissions of a discovery message, a number of subframe bitmaps during one discovery period, and information indicating a discovery offset. The method of claim 1, Receiving at least one of a synchronization signal and system information for D2D communication in a transmission resource determined based on the preset information from a neighbor UE; And Synchronizing with the neighboring UE using the received synchronization signal. The method of claim 5, Determining whether a received signal received power (RSRP) of the received synchronization signal is less than a threshold included in the preset information; And If the RSRP is less than the threshold value, further comprising transmitting at least one of a synchronization signal and system information for D2D communication in a transmission resource determined based on the preset information, The ID of the transmitted synchronization signal is determined based on the received system information. The method of claim 6, The received system information includes information indicating whether the neighboring UE is within the coverage; And when the neighboring UE is within the coverage, the ID of the transmitted synchronization signal is determined to be equal to the ID of the received synchronization signal. In a user equipment (UE) that is out of coverage serviced by a base station in a wireless communication network, A control unit which receives pre-configuration information for transmission of a discovery message and controls to transmit a discovery message in a transmission resource determined based on the preset information; And And a transceiver configured to receive the preset information and transmit the discovery message under the control of the controller. The preset information includes a pool list for transmitting the discovery message, and the transmission resource is determined from the pool list. The method of claim 8, The control unit is configured to detect a signal from a neighboring UE and determine whether a received signal received power (RSRP) of the detected signal is less than a threshold value, The threshold value is included in the preset information. The method of claim 9, And when the RSRP is less than the threshold, the controller is configured to transmit at least one of a synchronization signal and system information for D2D communication in a transmission resource determined based on the preset information. The method of claim 8, The preset information further includes at least one of a number of retransmissions of a discovery message, a number of subframe bitmaps during one discovery period, and information indicating a discovery offset. The method of claim 8, The control unit is configured to receive at least one of a synchronization signal for D2D communication and system information from a neighboring UE on a transmission resource determined based on the preset information, and to synchronize with the neighboring UE by using the received synchronization signal. UE. The method of claim 12, The controller determines whether a received signal received power (RSRP) of the received synchronization signal is less than a threshold included in the preset information, and if the RSRP is less than the threshold, based on the preset information. Is configured to transmit at least one of a synchronization signal and system information for D2D communication in the determined transmission resource, The control unit, characterized in that for determining the ID of the transmitted synchronization signal based on the received system information. The method of claim 13, The received system information includes information indicating whether the neighboring UE is within the coverage; And when the neighboring UE is within the coverage, the control unit determines the ID of the transmitted synchronization signal equal to the ID of the received synchronization signal. A method of performing device to device (D2D) discovery of a user equipment (UE) in a wireless communication network, Receiving a message including pre-configuration information for transmitting a D2D discovery message; Determining to act as a synchronization reference UE when receiving a command from a base station or meeting a predefined condition; Transmitting, in a transmission resource determined based on the preset information, a synchronization signal used for synchronization acquisition of time and frequency, and transmitting system information including transmission timing information of a discovery message; And Transmitting a discovery message in a transmission resource determined based on the preset information.

Images